Model be worthier than it's previous

I’m working on 3d landmark detection model
the training process works very well for el first 2 epochs and at the middle of the epoch 3 the loss starts to increase in an insane way and model results get much worth than it’s previous
what could be the reason of this

Is the training loss or the validation loss going up?
Could you post the loss curves for both losses?

for frist two epochs
trainloss inf -> 0.1 -> 0.03
validationloss inf->0.8->0.021
when this issue happens in the first 30% of epoch 3 i stop train to check the results in real images
the results was very bad compared to the previous model